A SIMPLE HARDWARE MODEL FOR THE DIRECT OBSERVATION OF VOLTAGE-CLAMP PERFORMANCE UNDER REALISTIC CONDITIONS

A new hardware cell model for electrophysiological recording has been constructed which allows for the assessment of voltage clamp accuracy in different recording situations. Each compartment consists of a capa citor in parallel with a variable resistor and can be connected to oth er compartments by a variable axial resistance. The simulated membrane resistance can be changed extrinsically by a command voltage input wh ich is optically coupled to the cell without any direct galvanic conta ct. Each compartment possesses a buffer amplifier which reads out the potential at the simulated membrane element, (e.g. 'somatic' or 'dendr itic' potential). The model allows for the direct observation of typic al situations and problems arising in electrophysiological experiments . We used the model to monitor deviations between the 'intracellular' and the command voltage, e.g. due to series resistance errors. We also used the model to simulate synaptic currents which were generated by triangular membrane conductance changes. The results demonstrate the s trong influence of synaptic location and series resistance on voltage clamp fidelity. The cell model is a new and easy-to-handle tool for th e observation of voltage control under realistic experimental conditio ns. (C) 1997 Elsevier Science B.V.